Supraventricular tachycardias (SVT)

CARDIOLOGY, Clinic A/P, adults, Clinic A/P, Peds, ECG, Hospital A/P, Adults, Hospital A/P, Peds

Tachyarrhythmias

Definition: Ventricular rate > 100. Based on QRS duration, they are divided into narrow-complex (QRS < 120 ms) or wide-complex (QRS >120 ms).

There are further divided into regular or irregular rhythms.

Mechanisms for tachyarrhythmias

  • Re-entry (most common mechanism)
  • Increased  or Enhanced Automaticity
  • Triggered Activity.

Approach to Supraventricular Tachycardias

For a stable patient, do a thorough workup that includes answering the following questions:

  1. “What are the odds? In a patient population with the characteristics fitting your patient, what is the most common arrhythmia?
  2. Is the rhythm regular or irregular?
  3. Are there discernible p waves?
  4. What is the morphology of the P-wave and what is the P wave’s relationship to the QRS complex?
  5. What is the RP interval?” From Washing Manual of Medical Therapeutics 32nd Edition.

 

Read this excellent article: http://www.aafp.org/afp/2015/1101/p793.html

Diagnosis and management of common types of supraventricular tachycardia. Am Fam Physician 2015;92(9):793-800.

N Engl J Med 2012;367(15):1438-1448.

“Vagal maneuvers and administration of adenosine are useful in the diagnosis and treatment of narrow-complex supraventricular tachycardias. Adenosine, a very short-acting endogenous nucleotide that blocks atrioventricular nodal conduction, terminates nearly all atrioventricular nodal reentrant tachycardias and atrioventricular reciprocating tachycardias, as well as up to 80% of atrial tachycardias. Although intravenous verapamil and diltiazem, which also block the atrioventricular node, have a potential diagnostic and therapeutic use in narrow-complex tachycardia, they may cause hypotension and thus are not a first choice in the emergency setting. Electrical cardioversion is reserved for patients who do not respond to adenosine. Antiarrhythmic agents are rarely necessary in the early management of supraventricular tachycardias, with the exception of the management of arrhythmias that have caused hemodynamic instability and that have not responded to electrical cardioversion. In these cases, procainamide and ibutilide can be used.” ABFM

 

Atrial Tachyarrhythmias

Atrial Tachycardia – Atrial activity is going at a rate of 120 -250

Atrial Flutter – atrial activity is going at 250-350

Atrial Fibrillation – atrial activity is > 350

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